WMOD00297

• Title: Hygroscopic Seeding in Oklahoma
• Date: 10/31/1971
• State: OK
• Weather Modification - Doc Type: Report

(

SUMMARY

.i

A large hygroscopic seeding capability was assembled and operated on the
Oklahoma Drouth Relief Operational Program on an emergency basis. The
system could dispense 30,000 pounds of material. It consisted of a C-97
aircraft and a dispenser system adapted from an Air !<'orce spray system used
in' icing tests. The aircraft operated out of Altus Air Force Base from mid-
August until early October. Seeding flights took place on 10 days. All the
operational aspects of the program worked satisfactorily.

There is no way to give a va,lid evaluation for the success of this operational
program. The seeding was done in the manner best judged to be useful, on the
basis of carefully-instrumented experimental programs performed elsewhere.
The seeding was done in conventional, daytime convective storms, varying
from marginally small clouds to a major system giving over 5" of rain.
The seeding coincided with a record wet September for Oklahoma~ The
primary target, the Lake Altus Reservoir, received no appreciable inflow
from its watershed - - the Qnly water it received was that which fell
virtually right on it. The main rains were at and south and east of the lake,
not in the body of its watershed.

(

This report describes the program and examines many of the concepts and
factors behind the hygroscopic seeding. It concludes that hygroscopic
seeding has a great potential for economic rewards, but cautions that many
answers are needed before its benefits can be properly utilized in the large,
complex conditions which give most precipitation. Developments are
needed in dispenser technology. mQdel/field experiments in simple clouds.
ascertaining the natural background of competing particles. and utilization
in complex conditions.

...

'.

L

i